DNA Structure and Genetic Flow

DNA Structure and Function

• DNA is the permanent storage of genetic information
• DNA copies are created in the form of RNA, which is used to create proteins
• Genes are units of genetic information
• One gene codes for one trait, while multiple genes may contribute to a single trait
• Enzymes and other proteins perform cellular activities
• Information in DNA is used to build proteins
• A single gene typically carries the instructions for a single protein, though alternative splicing exceptions occur
• Every cell contains the same DNA, but only certain genes are expressed

Flow of Genetic Information

• Information is stored in DNA
• Information is copied into RNA
• RNA is used to produce proteins
• Transcription converts DNA's nucleotide sequence into an RNA nucleotide sequence. This occurs in the nucleus
• Translation converts RNA's nucleotide sequence into a sequence of amino acids, forming a protein. This occurs in the cytoplasm by ribosomes.

Ribonucleic Acid (RNA)

• RNA is similar to DNA but differs in several key ways.
• RNA has ribose sugar instead of deoxyribose sugar
• RNA utilizes uracil instead of thymine
• RNA is a single-stranded molecule
• Various RNA types execute specific functions.
• Messenger RNA (mRNA) carries genetic instructions from DNA to ribosomes.
• Ribosomal RNA (rRNA) is a crucial component of ribosomes.
• Transfer RNA (tRNA) carries specific amino acids to ribosomes during protein synthesis.
• mRNA (messenger RNA): Temporary copy of a gene from DNA
• mRNA carries protein building instructions from the nucleus to the ribosomes
• mRNA degrades to nucleotides within an hour
• mRNA makes up 5% of total RNA
• Codon: Set of three nucleotides, "words" of the instructions

Ribosomal RNA (rRNA)

• rRNA is non-coding RNA
• rRNA converts mRNA's nucleotide sequence into an amino acid sequence.
• rRNA is synthesized in the nucleolus.
• rRNA makes up the majority of ribosomal subunits (65% RNA, 35% protein)
• rRNA (large and small subunits) combine in cytoplasm to carry out Protein synthesis
• rRNA accounts for 80% of total RNA

Transfer RNA (tRNA)

• tRNA is non-coding RNA
• tRNA delivers amino acids to ribosomes during protein synthesis
• tRNA has a distinctive three-dimensional shape, with a single amino acid attached at one end
• tRNA accounts for 15% of total RNA
• Anticodon: Set of three nucleotides in tRNA, complementary to the mRNA codon
• tRNA binds to the specific amino acid by aligning its anticodon to its corresponding mRNA codon

Messenger RNA (mRNA)

• mRNA is a temporary copy of a gene from DNA.
• mRNA sequences are necessary protein building instructions, that are carried from the nucleus to the ribosomes in the cytoplasm.
• mRNA is synthesized only when needed and is unstable with ribose sugar.
• mRNA degrades back to nucleotides within an hour.